Sleep mode rendering times
Nothing happens during sleep mode, not even the operating system is running.
Blender will not render because the computer is not powered on.

During Stand By the computer is in a low powered state with minimal energy consumption and little to no activity.

Depending on your version of the operating system the computer will either store the session in RAM memory or down to the hard drive reducing the power consumption to virtually zero.

If it serves as consolation Blender generally prevents Windows based operating systems, at least, from entering Stand By while running, so your renders will theoretically not be interrupted if the computer never enters sleep.